We have found a way to enable visual inheritance in our controls when they are used in Visual Studio 2005 / 2008. We have tested this solution in all the typical visual inheritance scenarios and haven't noticed any failures yet. But we cannot be completely sure that we have chosen the correct approach and thus we don't enable visual inheritance by default. What causes this doubt is that Microsoft disabled visual inheritance for its controls.
There is a DXDesignKeys tool shipped with the DXperience suite. It adds a new key to the registry and is capable of changing its state. When this key is present and enabled, Developer Express controls allow visual inheritance. If it is not present or disabled, visual inheritance is prohibited just as with standard controls (this is the default behavior). To launch the program, select its shortcut from the Start Menu\Programs\Developer Express v20XX vol Y\Components\Tools menu, where X and Y correspond to your DXperience version. Make sure to close Visual Studio prior to using the DXDesignKeys tool.
Note: starting with version 12.1 we renamed the DXDesignKeys tool to "WinForms 12.2 Design-Time Settings"
The use of XPO and server mode data source components on visually inherited controls
Can I use the grid on an inherited form or user control?
Troubleshooting design-time problems
What is the best way to set the same Look-and-Feel style of the entire application with DXperience for Windows Forms?